Tool retainer



June l, 1937. I E. B. LEAR 2,081,937

TooL RETAINER Filed Jan. 26,` 1935 I Tijl. ;u."

s i mm; l 3.a f V/,f/f f2 INVEN-roR EARL 5. 5A/'.

Patented June 1, 1937 PATENT OFFICE TOOL RETAINER Earl B. Lear, Detroit',

Pneumatic Tool Company,

Mich., assigner to Chicago New York, N. Y.,

a corporation of New Jersey Application January `26, 1935, Serial No. 3,555

,4 Claims.

IThis invention relates vto retainers for percussive rtools and more particularly toa retainer or holder for preventing la drill steel vfrom becoming detached from the fron-t head of a rock drill in which it is supported.

Among the objects of the invention are: the provision of .a steel holder which -is of simplified construction and has a minimum number of parts; the employment of resilient means for absorbing shocks transmitted to the holder; reductionof wear on the front head of the drill; the provision of retainer locking means which need not be permanently secured to the front head; increased strength and durability of the holder;

and convenience-in attaching the holder to and removing it from `the yfront head.

- The invention may be embodied in a U-shaped retainer whose arms are mounted for longitudinal sliding lmovement Within a pair of supportlng trunnions which are .mounted in the front head to rock with the retainer as ka unit. An important feature of the invention resides in locking means cooperating with the trunnions for yieldingly holding the retainer in its normal operative position. The llocking means is made effective bythe resiliency of the retainer arms.

lOther objects and features of the invention will appear more clearly from the following description `taken in connection lwith the accompanying drawing and a-ppended claims.

In the drawing, which illustrates one form of the invention:

Fig. 1 is a side elevational lview showing the invention applied to -a rock drill, fragmentary portions -of the iront head 'and drill steel being illustrated;

Fig. 2 is a sectional view as indicated by the arrows 2-2 -in Fig. l;

Fig. 3 -is a bottom elevational view of thedevice illustrated in Fig. l with Ythe drill steel shown in section;

v Fig. 4 is a cross-section looking upwardly, as

indicated bythe arrows 4--4 in Fig. l, certain parts being broken away; and

Fig. 5 is -an end view of one of the trunnions (see arrows 5-5 in Fig. 4) showing also a fragmentary portion of the front head.

Referring to Figs. 1 and 2, a drill steel I0 is provided with a shoulder or abutment Il engaging the lower end of a chuck l2 mounted in a bore I3 in the front head i4 of a rock drill cylinder. Shank l5 of the steel is of polygonal crosssection and has a sliding fit with the chuck. The upper end of the shank is adapted to receive 55 blows from a. piston extension I6. The structure thus far described does conventional rock drills.

In accordance with the present invention, the front head, 'near its lower extremity, is Aprovided with a Vtransverse bore -I1 whose axis lies in a plane at rig-ht angles to the axis of main bore i3. A cylindrical pin t9 extends across the lastmentioned bore at the midportion thereof. The front head is provided with a -threaded opening 20 and a counterbore 2| cooperating with the respective ends of the pin or bolt i9 to secure the latter in xed relation to the front head. While the bolt may be removed, if desired, removal thereof is not required in order to change tool holders, as will appear from the description which follows.

'I'he tool holder o r retainer 25, when viewed in side elevation is of U-shape having two vertical side arms 26, connected at their lower end -to a yoke portion 21 which partially encircles the drill steel I0. Upstanding lugs 28 are provided on the yoke at opposite sides of an opening 42li. These lugs are designed to resist the .tendency of the retainer to swing away from the steel when the collar Il strikes the yoke, as will be understood by those skilled in the art. A `collar 30 is formed integrally on each .of the arms 26 intermediate the ends thereof, and above ythe collar the arm comprises a reduced portion 3l preferably of cylindrical shape.

The -reduced ends 3l of the retainer arms are slidably mounted and received -within bores 32, each extending through the head 33 of a carrier member or trunnion34. Each trunnion has a cylindrical portion extending into the bore I1 in the front head. Compression springs 35, surrounding the upper ends 3l of ythe retainer arms, engage the trunnion heads 33 vand -nuts 31 thereby to force the arms 26 upwardly and hold the collars 30 in contact with the trunnion heads.

The operative position of the retainer is shown in Fig. 2 with the yoke portion positioned directly below Ithe collar Il on the drill steel. The-structure comprising the retainer, springs and tru-nnions may be swung asa-unit 4about the `axis ofthe trunnions in the direction of the arrow in Fig. 2, thereby to permit removal of the steel from the front head.

The invention includes means for yieldingly locking the retainer in the operative position shown in Fig. 2. The locking means comprises the pin I9 previously described, which cooperates with the inner end faces of the trunnions 34. As shown in Figs. 4 and 5 these end faces are provided with alined grooves 40 adapted to t not differ from that of a portion of the cylindrical surface of the locking pin I9. In order to force the trunnions toward each other, the arms 26 of the retainer 25 are so constructed that they have a slight inward tension when connected to the front head. This tension acts on the trunnions to resist rocking movement away from normal position and tends to cause the trunnions to snap into alinement with the pin I9.

Lubrication of the trunnions is made possible by a port 4I communicating with the main bore I3 in the front head.

In operation, the piston I6 delivers a succession of blows to the steel whose collar II may strike against the yoke 21 of the retainer 25. Springs 35 act as a shock absorber for the retainer by permitting it to yield in the direction of the blows. This not only minimizes wear on the front head but also prolongs the life of the retainer. When it is desired to change steels, the retainer is swung in the direction of the arrow in Fig. 2. As the retainer swings it carries with it the trunnions and encounters resistance offered by the locking pin I 9. This resistance, or yieldable locking means, may be overcome by forcing the retainer and trunnions until the latter are cammed outwardly by the pin I9 and grooves d.

The retainer may be replaced in a simple and eiective manner. As a i'lrst step, the nuts 31 are removed which frees the arms 35 to permit the retainer to drop. The trunnions are thereby set free and may also be replaced if desired.

It will be apparent to those skilled in the art that various changes and adaptations of the illustrative embodiment of the invention may be resorted to without departing from the spirit of the invention. For example, the front head referred to in the specification and claims need not necessarily be in one piece but may comprise several parts carried by the cylinder either in fixed relation or so connected relative thereto as to accomplish the results attained by the illustrative embodiment.

vWhat is claimed is:

l. In combination with a front head and a collared drill steel supported therein, a retainer having a yoke portion adapted to receive blows transmitted to it by the collar and having arms extending substantially parallel to the drill steel, said front head having a transverse bore extending in a plane at right angles to the axis of the drill steel, a pair of trunnions projecting into said bore from opposite ends thereof, said arms being connected with said trunnions to swing with the latter about the axis of said bore, and means connected with the front head and engaging one or both trunnions to provide a yieldable lock for the retainer in one position of its swinging movement, said locking means comprising a cylindrical pin carried by the front head and extending across said bore and engageable with a correspondingly-shaped groove formed in the end of one of the trunnions, and means for yieldingly holding said trunnion in engagement with the pin.

2. In combination with a front head and a collared drill steel supported therein, a retainer having a yoke portion adapted to receive blows transmitted to it by the collar and having arms extending substantially parallel to the drill steel, trunnions carried by said arms and projecting toward each other about a common axis, said front head having a transverse bore receiving the trunnions, a pin carried by the front head and positioned in said bore to engage the end faces of both trunnions, said end faces having cam surfaces engaging the pin, said arms being resilient and adapted to urge the trunnions toward each other, said cam surfaces being arranged to resist rotation of the trunnions away from a normal position.

3. In combination with a front head and a collared drill steel supported therein, a retainer having a yoke portion adapted to receive blows transmitted to it by the collar and having arms extending substantially parallel to the drill steel, trunnions carried by said arms and projecting toward each other about a common axis, said front head having a transverse bore receiving the trunnions, a pin carried by the front head `and positioned in said bore to engage the end faces of both trunnions, said end faces having cam surfaces engaging the pin, said arms being resilient and adapted to urge the trunnions toward each other, said cam surfaces being arranged to resist rotation of the trunnions away from a normal position, said trunnions having openings in which the arms are received, said openings permitting limited longitudinal movement of the arms with respect to the trunnions, and springs interposed between the trunnions and arms to resist such longitudinal movement in one direction.

4. In combination with a front head and a collared drill steel supported therein, a retainer having a yoke portion normally underlying the collar and having arms extending substantially parallel to the drill steel on opposite sides of the front head, said front head having alined transverse bores providing bearings, a pair of axially alined trunnions mounted to turn in said bearings and removable from the front head by movement away from each other, each trunnion having a bore in line with and receiving an arm of the retainer, whereby said retainer normally prevents removal of the trunnions from the front head, said arms being shaped to fit the trunnion bores, removable members secured to they free ends of the arms, springs between said members and the trunnions, and means yieldingly resisting rocking movement of the trunnions and arms away from the normal position, said means comprising a cam surface formed on one of the trunnions and a complementary cam element secured to the front head, said retainer' being resilient to force said trunnions toward each other and to hold said cam surface in engagement with said cam element.

EARL B. LEAR. 

